...I would wonder about a mechanic who says that a pump activating every time you step on brake is ok...I cannot believe either brake or pump system was designed to function as you describe...sounds like mechanic just does not know answer...as I said I will research and get back...it has my curiosity...JimB

 

....While I relate to your aversion to my reading or renewing old posts they are a goldmine of valuable information. Here is one you may benefit from. Regarding your vacuum pump activating whenever you apply the brakes...
....This is from a two (2) year old discussion and authored by an expert...
The vacuum system on our cars is a complex system with many functions. The Turbos are affected since the Wastgates are vacuum controlled, the source of the vacuum is both the engine and the vacuum pump. The vacuum pump supplies vac. to the "engine out" hoses, on both locations, either above steering rack or mounted on transmission (2004-2006) from there through check valves to other vacuum controlled devices, Brake Booster, Turbo Waste gates, Evaporator Purge Valves, Muffler Flaps...Note...The Waste Gates are not 100% controlled by vacuum, they have ability to be controlled by vac.) For most part boost pressure is routed to the front of the waste gate actuator. The higher the boost the more it pushes open the gate redirecting exhaust flow away from the Turbo Exhaust Wheel. Vac. is directed to back side of Wastgate for control, as needed. The vac. control is sent redundant because engine supplies the vac. when boost builds, and check valve closes, sealing in vac., a sensor checks the vacuum supply. If brakes are applied or supply of vac. drops, the vacuum pump in the drivers wheel well kicks in to resupply and top off...any questions...
You find out who is author so we can all express our appreciation...JimB

 

Hi Jim, thanks for the continued updates from you on this one. Since I am not car tech savvy, what would be a fix for this issue ? Thanks

 

Hello Jim,
If you are going to state the info as you have above, then please put it in quotations, and quote the Author, because at first it appears that you are stating the facts, which is not the case, so Please give credit where credit is due....

 

Yes Jim, PLEASE Tell us all.....

 

....Hello Johnny...just having a little fun with our Danish and South African friends who said some unkind things and characterized my posts as 100% Bull Sheet...at best they are only half right....if you read their posts, and I have read all of them, they are very proficient in the subject...BS that is, but I would never be so unkind as to criticize their contributions....
Back to subject: Vacuum
.....I was reporting from my notes and while not verbatim, I believe I related accurately the facts as told, purposely did not put in quotes because it is not word for word....In you opinion are the statements on the vacuum system accurate as I do not think the author meant them to say this is the totality of the vacuum system....eg, are any of the dashboard components vac controlled i.e. heater or ac as on some cars I have had...
.....Not as an excuse, but for the record I have very limited knowledge or experience with Forum etiquette, terms or procedures and have been relying on observation of what is acceptable by observation of what goes on here....
....Please bear with my little game as to the author of the Vacuum story, believe me there was no plagiarism done or intended...JimB

 

....Apply brake...vacuum pump comes on for 10 to 15 seconds...a number of people have reported this anomaly...when someone like PMS has it and has done 3 smoke tests...now that gets my curiosity. To state the obvious, something smells in Denmark...
There are only so many components or combination of components that could cause this malfunction. Bet there are guys here that know all about it...please clue us in...JimB

 

....just relocated the quote on subject of Vacuum utilization...The Author is a Bentley Technician Swflbt23 on Feb. 19, 2015..."When boost begins a check valve closes, sealing in the vacuum. There is a sensor that monitors the supply of vacuum....If you use the brakes or the vacuum supply drops, the vacuum pump kicks in to top off the supply." So apparently it is normal for the vacuum pump to operate upon applying brakes. I guess that means if the pump is unduly noisy, it may be wearing...we all get noisy as we age...
...On this same subject...when doing a smoke test, I believe it was another technician who said block off lines to rear exhaust flaps...anyone with idea what the purpose of that procedure...JimB

 

Had same problem on 2006 Flying Spur. Wife insisted I get it fixed. Bothered her. So, $3600 later it was fixed. Had to have some leaking line replaced. Most of expense was labor. Works fine now. Work done at Bentley dealer - for better or worse. Few indys work on these cars in Tennessee (most residents drive pickup trucks).